UT Electronic Theses and Dissertations

Permanent URI for this collectionhttps://hdl.handle.net/2152/11

This collection contains University of Texas at Austin electronic theses and dissertations (ETDs). The collection includes ETDs primarily from 2001 to the present. Some pre-2001 theses and dissertations have been digitized and added to this collection, but those are uncommon. The library catalog is the most comprehensive list of UT Austin theses and dissertations.

Since 2010, the Office of Graduate Studies at UT Austin has required all theses and dissertations to be made publicly available in Texas ScholarWorks; however, authors are able to request an embargo of up to seven years. Embargoed ETDs will not show up in this collection. Most of the ETDs in this collection are freely accessible to all users, but some pre-2010 works require a current UT EID at point of use. Please see the FAQs for more information. If you have a question about the availability of a specific ETD, please contact tsw@utlists.utexas.edu.

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    Horizon-based autonomous navigation and mapping for small body missions
    (2023-08) Hollenberg, Courtney; Russell, Ryan Paul, 1976-; Jones, Brandon A.
    This report expands upon a previously developed approach to simultaneously estimate asteroid physical characteristics and relative spacecraft state with limited prior knowledge using optical observations of the illuminated horizon from resolved imagery. The approach is intended for eventual autonomous use onboard a spacecraft. The asteroid surface is represented as a star-convex shape where the radial extent is a function of the input spherical coordinates. This unknown radial extent function is modeled as a Gaussian Process, which is formulated as a state space model that is well-suited to sequential Bayesian inference methods, namely, the Extended Kalman Filter. Early versions of this algorithm solidly demonstrated proof-of-concept, but this works aims to adjust and refine the filter equations to increase robustness to larger nonlinearities. Efficacy of the reworked estimator is demonstrated through Monte Carlo simulations.
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    SCALEX: SCALability EXploration of multi-agent reinforcement learning agents in grid-interactive efficient buildings
    (2023-08) Almilaify, Yara Sami; Nagy, Gyorgy Zoltan
    The transition to renewable energy sources and the decarbonization of buildings bring new challenges to grid-interactive efficient building (GEB) communities such as grid stability issues and energy system integration. The dynamic and stochastic nature of intermittent renewable energy production makes it challenging for conventional building control systems to maximize them. To overcome this, advanced control architecture and energy storage are utilized to achieve energy flexibility. Reinforcement learning (RL) offers potential solutions, but its scalability and computational demands in large-scale settings remain unclear. This thesis examines the scalability of Soft-Actor Critic (SAC) in multi-agent systems, comparing decentralized-independent SACs and centralized SACs using CityLearn, an OpenAI Gym environment. We consider neighborhoods consisting of 2 to 64 single-family residential buildings, each equipped with cooling and heating storage devices, domestic hot water storage devices, electrical storage devices, and solar PV systems. In this work, we delve into the challenges faced by these controllers when scaled in a multi-agent system. Our findings suggest that decentralized-independent controllers outperform the centralized controller with an increasing number of buildings. We also show that the performance on the building level can differ from the aggregated performance.
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    Impact of prechlorination pH on Pb(II)-NOM complexation and lead release in drinking water distribution systems
    (2023-08) Goodman, Jacob (Ph. D. in environmental and water resources engineering); Katz, Lynn Ellen
    The presence of Pb in drinking water resulting from corrosion of lead pipes, solder and fixtures poses a significant threat to public health and safety. Pb is a potent neurotoxin that can impair the cognitive development of children at low concentrations in the bloodstream. During the corrosion of distribution system components containing Pb, precipitate scales form on the interior surfaces of pipes in the distribution system providing a protective barrier between the bulk solution and the pipe surface; the amount of dissolved Pb²⁺ is controlled by the thermodynamics and kinetics of precipitation/dissolution of the particular Pb scales in the system. The solubility and composition of Pb scales phases residing on the pipe surfaces are a function of the background water chemistry (including pH, redox potential and ligand types and concentration). Therefore, considering the conditional stability of lead scales is crucial when making changes to water treatment processes, as alterations in water quality can significantly disrupt the stability of scales in the DWDS, leading to elevated lead concentrations. In distribution systems that employ monochloramine to provide residual disinfection, the formation of Pb(II) scales such as cerussite (PbCO₃) and hydroxyapatite are favored depending on the background water composition (e.g., phosphates added for corrosion protection or carbonate present). Utilities that chloraminate typically implement a prechlorination step in which free chlorine reacts for a specified time prior to ammonia addition to meet disinfection requirements. During the prechlorination step, free chlorine can react with natural organic matter (NOM) to promote Pb release. The formation of NOM-Pb complexes increases the total soluble Pb in distribution systems containing Pb scales. However, before NOM enters the drinking water distribution system (DWDS) oxidation or nucleophilic substitution of NOM functional groups during prechlorination can decrease the extent of Pb(II)-NOM complexation. The relative impact of these processes on Pb(II) concentrations in drinking water distribution systems must be understood for effective Pb control in DWDS’s containing NOM. In this study, the impact of Pb-NOM complexation on Pb(II) release from cerussite (PbCO₃), a Pb scale phase that can form in the DWDS, is studied in batch dissolution experiments with and without prechlorination. Prechorination of the water containing NOM for a 30-minute contact time decreased the amount of Pb released in the presence of NOM with greater reduction at lower pH. The trends in pH were consistent with the greater reactivity between free chlorine and NOM at lower pH. Additionally, excitation emission matrices (EEMs) and near edge x-ray fine structures (NEXAFS) spectroscopy confirmed that chlorination of the NOM led to destruction of electron rich aromatic moieties that function as prominent ligands in Pb(II)-NOM complexation Further, it was found that fewer in number of disinfection byproducts (DBPs) precursors were generated upon reaction of chlorine and NOM at lower pH conditions. These results demonstrate the potential for chlorination to reduce Pb(II)-NOM complexation. The concentrations of total soluble Pb observed in the batch dissolution experiments ranging from 40 ppb to 600 ppb are not representative of dissolved Pb concentrations in the water distribution system as a Pb concentration of 15 ppb necessitates the implementation of corrosion control measures. Further studies are needed to assess the relative impact of Pb(II)-NOM complexation under continuous flow conditions that more closely mimic pipe flow through conditions representative of water distribution system conditions.
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    Material property extraction procedure for electromomentum coupled metamaterials
    (2023-08) Casali, Matthew A.; Haberman, Michael R. (Michael Richard), 1977-
    Electromomentum (Eμ) coupling is a material response that couples the macroscopically observable time-varying electric field to the momentum of the material. This unique behavior has been shown theoretically to result from dynamics at subwavelength length-scales due to asymmetries in heterogeneous piezoelectric materials. Electromomentum coupling is of interest to the engineering and scientific community for its ability to simultaneously sense both the acoustic pressure and particle velocity at a single point in space, thus enabling the creation of vector sensor devices using a single material. This thesis presents a study of the characterization of this novel transduction behavior through multiscale models and numerical experiments. The material models include analytical and finite element methods that extend the work of Pernas-Salomón et al. [Wave Motion, 106, 102797, (2021)]. The models simultaneously provide insight into the subwavelength behavior that leads to Eμ coupling on the macroscopic scale as well as metrics of the coupling strength. Additionally, these models are employed in a design strategy to maximize Eμ coupling demonstrated by a heterogeneous piezoelectric scatterer using readily available materials and easily manufactured geometries. To achieve this, a series of candidate designs are modeled and their Willis and/or Eμ coupling is quantified. The models are then employed to design an experimental method to characterize Eμ coupling of a sample using a water-filled impedance tube. The impedance tube measurement procedure presented in this work is a generalization of existing methods used to infer the frequency-dependent material properties of a sample from measurements of its scattering coefficients and associated property extraction algorithms. Namely, the works of Song and Bolton to measure the complex impedance and wavenumber or phase speed and attenuation [J. Acoust. Soc. Am., 107(3), pp. 1131-1152, (2000)], Fokin et al. to measure the complex-valued density and bulk modulus, including negative values, [Phys. Rev. B, 76(14), 114302, (2007)], and Muhlestein et al. who extended the work of Fokin et al. to measure Willis coupling in addition to density and bulk modulus [Nat. Commun., 8, 15625, (2017)]. This work also considers practical details such as dispersion, hydrophone calibration, and sample mounting, that are specific to measurements in a water-filled impedance tube and their influence on the accuracy of measurements of scattering coefficients using this apparatus, ending with recommendations for future measurements.
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    Extraction of the underlying material response of pseudoelastic NiTi and its application in numerical simulations
    (2023-08) Greenly, Jacob Louis; Kyriakides, S.
    In certain temperature regimes NiTi exhibits pseudoelasticity, meaning that after being loaded to strains of 6-7% it can return to its original configuration. This behavior is produced by the reversible solid-state phase transformation between the austenitic (A) and martensitic (M) phases. During isothermal tensile testing the response produces a closed hysteresis that traces two stress plateaus corresponding to localization and propagation of transformation front(s). Hallai and Kyriakides (2013) extracted the underlying up-down-up material response during the A [rightwards arrow symbol] M transformation from an experiment on a laminate composed of an unstable NiTi core and hardening facestrips. In these experiments, the laminates were plastically deformed to a strain of about 6%. To obtain the underlying response during the reverse M [rightwards arrow symbol] A transformation, the laminate must be reverse loaded back to zero, resulting in compressive forces in the hardening facestrips which ultimately lead to the laminate buckling. This thesis presents a new experimental setup to prevent buckling by laterally supporting the laminate during reverse loading. From this test, the complete underlying NiTi response is extracted and exhibits the expected softening branches during both the A [rightwards arrow symbol] M and M [rightwards arrow symbol] A transformations, with each branch having a Maxwell stress similar to the corresponding experimental plateau stress level. The full response is used to calibrate a custom constitutive model that produces a fit based completely on a measured response for the first time. Simulations of the isothermal tensile tests using this fit capture the measured response and localized deformation pattern to the greatest extent thus far. The fit is also used to conduct a parametric study on the effect the hardening facestrip thickness has on the overall laminate response, and possible changes to aid future users of this method are identified. The new method presented can replace the previously empirical model calibration method and enable more confident modeling of the unstable behavior of SMA structures through the use of measured data.
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    Enhancing worker management and supporting external tasks in crowdsourced data labeling
    (2023-12) Thapa, Sukanya; Lease, Matthew A.
    Human data labeling is key to training supervised machine learning (ML) models. We propose a new software infrastructure layer to augment capabilities of Amazon’s SageMaker Ground Truth (GT) data labeling platform. Whereas crowdsourced annotation via Amazon Mechanical Turk (MTurk) is well-established, Amazon’s more recent GT platform is less known but specifically designed to support ML annotation. Differentiating features include a curated “public crowd” sourced from MTurk, and integrating human labeling into Amazon’s broader SageMaker ML tool suite, which provides an end-to-end pipeline for training and deploying ML services. Key features of our software layer include: 1) continuous worker performance monitoring wrt. Requester gold labels; 2) automatically restricting task access when performance standards are not met; 3) geographic-based restriction of task access to US-based workers; and 4) the ability to conduct external tasks off-platform while sourcing workers from GT and continuing to use GT’s payment system. Our design seeks to streamline Requester experience with minimal changes, and to utilize a sustainable software design to ease long-term management, extension, and maintenance. More generally, design goals center on promoting efficient, user-friendly, and quality-focused data labeling with crowdsourced annotators.
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    Aligning data with organization's and workers' goals: designing data labeling systems for social service case notes
    (2023-08) Gondimalla, Apoorva; Lee, Min Kyung, Ph. D.
    In the era of data-driven approaches in non-profit and social service government organizations, prevailing data collection methods for performance and funding reports are ineffective and unsatisfactory for both workers and organizational leaders. Within social service provision, evaluating outcomes necessitates intricate subjective assessments, resulting in social workers equipped with profound insights into services and outcomes shouldering the burden of manual record-keeping. Simultaneously, organizational leaders grapple with insufficient data for reporting. While existing research explores data collection challenges, there is a dearth of studies that delve into solutions for enhancing these systems. This study examines data labeling systems that encapsulate client interaction outcomes, focusing on caseworkers aiding those experiencing homelessness. Despite advances in domains such as crowd-sourced data labeling, their approaches often fail to consider the unique values and contexts of social workers who intertwine data labeling with their caregiving work. By employing interviews, ideation, and a speed-dating approach, we scrutinize preferences, potential solutions, and challenges in crafting efficient data labeling systems. We evaluate 15 diverse design ideas across four dimensions: alignment with case management objectives, comprehensive portrayal of caseworker contributions, clarity in data labels, and enhancements in labeling process usability. Our findings highlight the collective aspiration for data labeling systems that cater to varied stakeholder information goals while effectively capturing nuanced casework details, streamlining data labeling into a seamless, efficient task. Leveraging our insights, we offer design implications for enhancing data labeling systems, aligning them with the objectives of both organizations and workers.
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    Instruction Scheduling for EDGE Architectures
    (2005-08-15) Kushwaha, Sundeep Kumar; McKinley, Kathryn S.; Burger, Doug
    Instruction scheduling is a code reordering transformation used to hide latencies
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    The politics of representation and collaboration : El Río, a Smithsonian folklife festival and traveling exhibition
    (2005-05-21) Peché, Linda Ho; Strong, Pauline Turner, 1953-
    The problem of representation has been a contested issue in both contemporary anthropology and the museum field. I analyze the development of a Smithsonian festival and exhibition called “El Río: Culture and Environment on the Rio Grande/río Bravo Basin” to explore the following questions. Is it possible to disconnect modern representational practices from the historical roots of human display for entertainment? Can the individuals represented speak for themselves within this framework? It is extremely difficult to disentangle current representations from nineteenth century exhibition with the use of the same presentational techniques. However, the El Río festival and exhibition curators are using interaction and collaboration as methods for the inclusion of peoples that previously had no say in institutional representations of their cultures
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    Exploring protein biochemistry with deep learning
    (2023-12) Kulikova, Anastasiya Vitalievna; Wilke, C. (Claus); Davies, Bryan W.; Klivans, Adam R.; Russell, Rick
    Deep learning has become widely used in biological sciences. More specifically, the development of protein deep learning models has leveraged the evergrowing collection of biological data to learn the patterns that govern protein biochemistry. Here, we focus on the assessment of different protein deep learning models to better understand each of their capabilities, benefits and drawbacks. Our work aims to provide insights for future protein engineering efforts and for the discovery of protein homologs. In Chapter 2 we assessed a structure-based protein ML model in its ability to make biochemically meaningful predictions and tested weather or not the model can predict specific allowed amino acids in a protein. We compared the performance of models trained on different input sizes and correlated model predictions with natural variation in order to better understand how these models learn protein structure and biochemistry. In Chapter 3, we compared the predictions of two structure models and two language models to determine if different protein representations affect what information each model type learns and their performance. Finally, in Chapter 4, we apply a sequence-based protein model to searching for antibacterial microcin peptides in bacterial genomes.
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    U.S. foreign policy and Iraqi Kurdish separatism
    (2005-08-15) Hodachok, Eric Nestor; Zilkha, Avraham
    This thesis addresses United States foreign policy toward Iraq, focusing on U.S. policy toward the Iraqi Kurds in the latter half of the 20th century. Specifically, it examines how U.S. policy has responded to Iraqi Kurdish separatism from the post World War II period until the present. By examining U.S. foreign policy towards Iraqi Kurds, it is possible to trace the evolution of U.S. policy’s response to Iraqi Kurdish separatism from the post World War II period until the present, especially the revolution which U.S. policy toward the Iraqi Kurds underwent in the 1990s. The sources used in this thesis consist specifically of U.S. Department of State documents, U.S. Central Intelligence Agency documents, U.S. Congressional documents, committee hearings, and staff reports, White House documents, as well as various other sources
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    Internal wild : a collection of poetry
    (2005-05-21) Kim, Yung Won; Wevill, David, 1935-
    Sectioned by texture and mood, Internal Wild is a collection of poetry that observes aspects of romantic, as well as filial, love in America, Europe, Asia next to the lush environs of the natural world. The second part of the thesis is a collection of three short stories, entitled Pragmatic Romanticist. The first story (“Going Goldberg”) is about a young classical concert pianist who tows the fragile line between her art, musical competition, family, and self-possession. “Happy Birthday in Ho Chi Minh City” tells the story of a newly married New York City couple, an unexpected revelation at the husband’s birthday dinner, and the personal politics of their marriage. The third story, “Fascinating Lawns,” is a darkly comic homage to eclectic and somewhat eccentric family reunions as it relates to the conflicted intimacies of a couple looking for mutual shelter. The final part of the thesis includes a creative process essay which reflects on the aesthetics, influences, and technique of the writing. An author vita is included at the end
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    Abundance, production and carbon dynamics of the seagrass, Thalassia testudinum in Corpus Christi Bay, Texas
    (1995) Lee, Kun-seop; Dunton, Kenneth H.
    The seasonal production dynamics of the subtropical seagrass, Thalassia testudinum, were examined through measurements of biomass, leaf growth and carbohydrate carbon content from plants collected in Corpus Christi Bay from December 1993 to March 1995. Daily photon flux densities (PFD) showed strong seasonal variations, ranging from 9.6 mol m⁻² d⁻¹ in April to 21.7 mol m⁻² d⁻¹ in July. Shoot density and biomass changed significantly with season; values ranged from 321 shoots m⁻² (454 g dry wt m⁻²) in March to 531 shoots m⁻² (885 g dry wt m⁻²) in September. Rhizome tissues tended to have the highest biomass while root tissue had the lowest. Leaf productivities showed significant seasonal variation that were strongly correlated with temperature, ranging from 0.07 g dry wt m⁻² d⁻¹ in December to 5.6 g dry wt m⁻² d⁻¹ in July. Chlorophyll (chl) concentrations were significantly higher and chl a:b ratios lowest during the spring/summer period of maximum photosynthetic production and growth than during winter. Soluble carbohydrate carbon content was highest in rhizome tissues (111-203 mg C g⁻¹ dry wt) and lowest in leaf tissues (46-70 mg C g⁻¹ dry wt), which is consistent with the rhizome's role as a carbon storage tissue. Soluble rhizome carbohydrate carbon content increased rapidly during June and July, which coincided with high water temperatures, underwater irradiance and blade chlorophyll concentrations. During winter and early spring, rhizome carbohydrate carbon content dropped nearly 50%, suggesting that these reserves were mobilized for maintenance and growth. Estimated annual biomass production of Thalassia testudinum in Corpus Christi Bay over the period of this study was 1320 g dry wt m⁻² yr⁻¹, equivalent to 422 g C m⁻² yr⁻¹. To assess the effects of light reduction on Thalassia testudinum, shade screens were used to reduce underwater light to 1628 mol m⁻² yr⁻¹ (14% of surface irradiance, SI) and 864 mol m⁻² yr⁻¹ (5% SI) starting in April 1993. All plants subjected to 5% SI died after 200 days and over 99% of plants receiving 14% SI died by the end of the experiment (490 days). Blade widths of plants in the controls ranged from 6.4 to 7.0 mm, and decreased to 4.7 mm as a result of light reduction. Leaf production rates were significantly higher in control plants compared to plants within the 14% and 5% SI treatments, with all plants showing a seasonal trend with high productivity in July and low productivity in April. Blade chlorophyll concentrations increased, while the chl a:b ratio decreased with reduced light level. In both light treatments rhizome soluble carbohydrate carbon content was 50% lower and leaf carbohydrate carbon content was about 15% lower than controls, while the root carbohydrate content did not differ significantly between treatments and controls (no decrease in structural carbohydrate carbon content was noted between treatments). Pore water ammonium and sulfide concentrations in the shaded cages were significantly higher than in control cages. Thalassia testudinum in Corpus Christi Bay exhibited a strong seasonal growth cycle in which changes in rhizome carbohydrate reserves and chlorophyll content may be under endogenous control as triggered by a combination of temperature and/or light period. In contrast to the seagrass Halodule, Thalassia maintained a larger carbohydrate reserve and exhibited a stronger physiological response to light reduction, which may contribute to its competitive superiority
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    Master's thesis recital (tuba)
    (2024-04-07) Wilner, Evan; Unable to determine
    Panda in love / Lindberg -- Quill of the soul / Wilner -- Six pack / Meador -- Troll tuba / Hogberg
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    Organic and inorganic carbon in the recent sediments of the open Gulf, barrier island and bay environments, Mustang Island, Texas
    (1960) Jones, Darrell K., 1935-; Kornicker, Louis S., 1919-2018
    The sediment at both surface and one-foot depths in cores from the Gulf of Mexico, Mustang Island, and Corpus Christi Bay Texas, was analyzed by a wet combustion method to determine the per cent of carbon by dry weight in the organic fraction (organic carbon) and in the carbonate fraction (inorganic carbon). The statistical "t" test showed a significant difference (P = 0.05) between the mean per cent organic carbon content of the surface sediments from 1) Gulf (0.52%) and island (0.17%) and 2) island (0.17%) and bay (0.58%) and of one-foot sediments from 1) Gulf (0.29%) and island (0.11%) and 2) island (0.11%) and bay (0.44%). A significant difference was also found between the means of the per cent of carbonate carbon in surface sediments from 1) Gulf (0.50%) and island (0.09%) and 2) island (0.09%) and bay (0.68%) and in sediments from Gulf (0.32%) and bay (0.68%). A comparison of the means of the per cent of carbonate carbon in sediments at the surface (0.50%) and one-foot depths (0.32%) of all Gulf cores showed a significant difference at the 0.05 probability level. The organic carbon and inorganic carbon content of the sediment may be useful in distinguishing between Gulf and barrier island, and bay and barrier island sediments in the geologic record, but probably not for distinguishing between Gulf and bay environments
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    Doctoral thesis recital (percussion (lecture))
    (2024-03-31) Wheeler, Sam; Unable to determine
    Electronic Implements and Other Musical Prosthetics: Perspectives on Electronic Integration in Percussion Repertoire (lecture and performance)
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    Doctoral thesis recital (violin)
    (2024-04-14) Han, Na Lee; Unable to determine
    Violin sonata no. 9 op. 47 in A major : "Kreutzer" / Ludwig van Beethoven -- Violin sonata in G minor / Debussy.
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    Doctoral thesis recital (piano (chamber))
    (2024-04-12) Lee, Chanwoo; Unable to determine
    Piano trio in G major / Claude Debussy -- Piano trio in G minor op. 15 / Bedřich Smetana
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    Masters thesis recital (flute)
    (2024-04-13) Robinson, Nina; Unable to determine,
    Au-delà du temps / Yuko Uebayashi -- Sonata for flute and piano in C-sharp minor, op. 64 / Mél Bonis -- Fanmi imèn / Valerie Coleman -- Concertino for flute in D major op. 107 / Cécile Chaminade.

Authors of these ETDs have retained their copyright while granting the University of Texas Libraries the non-exclusive right to reproduce and distribute their works.